完善项目导入、模板与分割工作区交互

- 增强 DICOM/视频项目导入与演示数据：DICOM 按文件名自然顺序处理，导入后展示上传与解析任务进度，恢复演示出厂设置保留演示视频和演示 DICOM 项目，并补充 demo media seed 逻辑。

- 完善项目管理：项目支持重命名、删除、复制，删除使用站内确认弹窗，复制支持新项目重置和全内容复制，DICOM 项目不显示生成帧入口。

- 完善 GT Mask 与导出链路：只支持 8-bit maskid 图导入，非法/全背景图明确拒绝，尺寸自动适配，高精度 polygon 回显；统一导出默认当前帧，GT_label 使用 uint8 和真实 maskid，待分类 maskid 0 与背景一致。

- 完善分割工作区交互：新增画笔和橡皮擦并支持尺寸控制，移除创建点/线段入口，工具栏按类别分隔，AI 智能分割使用明确 AI 图标，取消黄色 seed point，清空/删除传播 mask 后同步清理空帧时间轴状态。

- 完善传播与时间轴：自动传播使用 SAM 2.1 权重任务，参考帧无遮罩时提示，传播历史按同一蓝色系递进变暗，删除/清空传播链时保留人工或独立 AI 标注来源。

- 完善模板库：新增头颈部 CT 分割默认模板，所有模板保留 maskid 0 待分类，支持鼠标复制模板、拖拽层级、JSON 批量导入预览、删除 label 和站内删除确认。

- 完善用户与高风险确认：用户改密码、删除用户、恢复演示出厂设置和清空人工/AI 标注帧均改为站内确认交互，避免浏览器原生 prompt/confirm。

- 补充前后端测试与文档：更新项目、模板、GT 导入、导出、传播、DICOM、用户管理等测试，并同步 README、AGENTS 和 doc 下实现/契约/测试计划文档。

backend/routers/admin.py

@@ -9,7 +9,6 @@ from sqlalchemy.orm import Session
 
 from config import settings
 from database import get_db
-from minio_client import upload_file
 from models import Annotation, AuditLog, Frame, Mask, ProcessingTask, Project, Template, User
 from routers.auth import ensure_default_admin, hash_password, require_admin, write_audit_log
 from schemas import (
@@ -20,13 +19,19 @@ from schemas import (
     DemoFactoryResetRequest,
     UserOut,
 )
-from statuses import PROJECT_STATUS_PENDING
+from services.demo_media import (
+    DEMO_DICOM_PROJECT_NAME,
+    DEMO_VIDEO_PROJECT_NAME,
+    create_parsed_dicom_demo_project,
+    create_unparsed_video_demo_project,
+    demo_dicom_files,
+)
 
 router = APIRouter(prefix="/api/admin", tags=["Admin"])
 
 VALID_ROLES = {"admin", "annotator", "viewer"}
 DEMO_RESET_CONFIRMATION = "RESET_DEMO_FACTORY"
-DEMO_PROJECT_NAME = "Data_MyVideo_1"
+DEMO_PROJECT_NAME = DEMO_DICOM_PROJECT_NAME
 
 
 def _normalize_role(role: str | None) -> str:
@@ -191,7 +196,7 @@ def reset_demo_factory(
     db: Session = Depends(get_db),
     admin_user: User = Depends(require_admin),
 ) -> dict:
-    """Reset a demo deployment to one admin account and one unparsed demo video project."""
+    """Reset a demo deployment to one admin account, the demo video, and the demo DICOM project."""
     if payload.confirmation != DEMO_RESET_CONFIRMATION:
         raise HTTPException(status_code=400, detail="Invalid reset confirmation")
 
@@ -200,6 +205,11 @@ def reset_demo_factory(
             status_code=409,
             detail=f"Demo video not found: {settings.demo_video_path}",
         )
+    if not demo_dicom_files(settings.demo_dicom_dir):
+        raise HTTPException(
+            status_code=409,
+            detail=f"Demo DICOM series not found: {settings.demo_dicom_dir}",
+        )
 
     requested_by = admin_user.username
     preserved_admin = ensure_default_admin(db)
@@ -226,37 +236,39 @@ def reset_demo_factory(
     if not preserved_admin:
         raise HTTPException(status_code=500, detail="Default admin was not preserved")
 
-    project = Project(
-        name=DEMO_PROJECT_NAME,
-        description="默认演示视频，尚未生成帧",
-        status=PROJECT_STATUS_PENDING,
-        source_type="video",
-        parse_fps=30.0,
-        owner_user_id=preserved_admin.id,
+    video_project = create_unparsed_video_demo_project(
+        db,
+        owner=preserved_admin,
+        video_path=settings.demo_video_path,
+        project_name=DEMO_VIDEO_PROJECT_NAME,
     )
-    db.add(project)
-    db.flush()
+    video_project.frame_count = 0
 
-    with open(settings.demo_video_path, "rb") as file_obj:
-        data = file_obj.read()
-    object_name = f"uploads/{project.id}/{os.path.basename(settings.demo_video_path)}"
-    upload_file(object_name, data, content_type="video/mp4", length=len(data))
-    project.video_path = object_name
-    project.thumbnail_url = None
-    project.original_fps = None
-    db.commit()
+    dicom_project = create_parsed_dicom_demo_project(
+        db,
+        owner=preserved_admin,
+        dicom_dir=settings.demo_dicom_dir,
+        project_name=DEMO_PROJECT_NAME,
+    )
     db.refresh(preserved_admin)
-    db.refresh(project)
+    db.refresh(video_project)
+    db.refresh(dicom_project)
+    video_project.frame_count = len(video_project.frames)
+    dicom_project.frame_count = len(dicom_project.frames)
+    projects = [video_project, dicom_project]
 
     write_audit_log(
         db,
         actor=preserved_admin,
         action="admin.demo_factory_reset",
         target_type="project",
-        target_id=project.id,
+        target_id=dicom_project.id,
         detail={
-            "project_name": project.name,
-            "video_path": project.video_path,
+            "project_names": [project.name for project in projects],
+            "video_path": video_project.video_path,
+            "dicom_path": dicom_project.video_path,
+            "source_types": [project.source_type for project in projects],
+            "frame_counts": {project.name: len(project.frames) for project in projects},
             "deleted_counts": deleted_counts,
             "requested_by": requested_by,
         },
@@ -264,7 +276,8 @@ def reset_demo_factory(
 
     return {
         "admin_user": preserved_admin,
-        "project": project,
+        "project": dicom_project,
+        "projects": projects,
         "deleted_counts": deleted_counts,
         "message": "演示环境已恢复出厂设置",
     }